I recently purchased a 2002 Golf GLS from a guy in Phoenix. Before he sold it to me, he was having troubles with the check engine light coming on, along with a flashing glow plug light. He took it to the mechanic, who gave him a "VCDS VAG/VAS Emulator" print out showing the following information:

The owner then agreed to having the mechanic replace and reprogram the ECU, as well as the Throttle Actuator (reciept shows PN "6Q1 721 503H"). This supposedly fixed the problem, and the CEL and GP lights went off, and I purchased the car. After driving 1000 miles down the road, the same problem shows up again: CEL is solid, GP light is flashing, and an OBDII reader gives code P0228. The car still idles, and drives just fine, and I routinely get 47+mpg. I'd just like to figure out what is causing this problem and what I can do to fix it. When switching the key to the on position, the GP light goes out almost immediately. I'm going on a road trip to North-Eastern Washington state in a few days, and am worried that my lack of glow plugs may be an issue with the sub-freezing temperatures I'll be living in for a few days.

What I've tried:
- I reset the code. It comes back within 100 miles.
- I took the 6-pin wiring harness out from the throttle position sensor and tested the voltages as described in the lower right hand corder of the attached page from the manual. The readings are supposed to be "4.5 volts minimum." The readings were as follows:

- I did a continuity test between pin 1 on the TPS harness and pin 63 of the ECU harness, which tested fine.
- I did another continuity test between pin 5 on the TPS harness and pin 70 of the ECU Harness, which also tested fine.

Any thoughts? Like I said, the reciepts show the ECU and Throttle Actuator being replaced less than 2000 miles before this started happening again. What else can I check or do to solve this problem? Any advice or information would be greatly appreciated. Thanks in advance!

You need to check for a voltage drop on the wire(s) while the circuit is all plugged in during normal operation.

You may have a chaffed wire problem in the dash somewhere as DanG144 suggested.

If that is the case, you probably would be better off to make a new harness to the pedal position sensor and tap into the ECU harness somewhere in the cowl area.

If you want to take the time, you can try and trace the wiring harness from the ECU in the cowl, through the firewall junction, and into the dash harness, but it may be quite buried under other components such as the pedal assembly.

With a proper scan tool, you could check the freeze-frame when the DTC was set and try and duplicate that condition (time, temp, etc) and try watching the data blocks while wiggling the harness about and see if you find a glitch somewhere. Funny how so much experience with crappy American cars' wiring pays off with diagnosing problems like this.

Several years ago on my 2001 Jetta TDI I had similar problem with CEL, flashing GP light and limp mode. When the code was scanned it too pointed to the throttle position sensor. I was due for a brake switch recall, and I had the dealer perform that. Since then I never had that code, flashing glow plug light or limp mode.

2000Jetta, with stick shift.
Engine "cut-off" the other day while I was going along about 40 mph.
Code thrown was VW 18047 ( I forgot the "P" code), anyhow the description was "Throttle position sensor signal implausable".
I recalled a while ago (2 years?) someone took their position sensor apaprt and tweaked the little fingers that run on the carbon 'resistors' and all was well again. I did that. Cleared the codes and all seems OK.

BUT...I also checked the voltages at the connector as mentioned above, and likewise only got a miniscule voltage at the terminal 1-to-5 test. All others exceeded 4.5 volts.
I first suspect an error in the manual as inspection of the schematic showing what terminals 1 and 5 connect through leads me to think a voltage here with the position sensor unplugged should not happen.
CAN ANYONE comment on this? Maybe the terminal 1-5 voltage should be there with another type sensor, but for what I have it seems questionable.

PS, Eyework. It's hard to get to those 2 top nuts, isn't it? VW must be in cahoots with a chiropractor!!

BTW, NAPA lists a pedal and sensor assembly for this app. for $139.xx and you don't have to pay shipping!! NAPA # 2-80094. I bet some big stores will have it in stock!!

Yes, I helped put my youngest Son into his 2002 Jetta TDI last summer and I thought the ~2-seconds
hesitation that would happen for me when going quickly from brake to accelerator was not quite right...
and then yesterday after stopping at an intersection the ECM apparently refused to acknowledge my Son's attempt to then accelerate on through.
It did NOT stall but he had to turn the key off and then restart and then it ran OK!

So I'm the type to do as "Warthog" did in POST #6 above... : tweaked the little fingers that run on the carbon 'resistors' For certain I want to get to this before he & his Wife makes any out of town trips! Thus far his symptoms are merely a bother... but IF it did this in the middle of 5 lanes of freeway traffic and then the ECM do a complete shut down... well that's #@%*& bad news!Q - Does anyone know more about this recall on the brake switch??Regads,Sam

VW had several brake light switch recalls on my 2001 MKIV Jetta TDI manual trans. The latest version is a solid green brake light switch. It is not difficult to replace, but you need to pull off a couple interior panels below the steering wheel then a metal plate behind that. The switch at the dealer only cost me a few dollars. The brake light switch is removed by rotating it out of its holder adjacent to and in front of the brake pedal. Again I had the check engine light, flashing glow plug light and limp mode with a manual trans.

VW had several brake light switch recalls on my 2001 MKIV Jetta TDI manual trans.
The latest version is a solid green brake light switch.
It is not difficult to replace, but you need to pull off a couple interior panels below the steering wheel then a metal plate behind that.
The switch at the dealer only cost me a few dollars.
The brake light switch is removed by rotating it out of its holder adjacent to and in front of the brake pedal.
Again I had the check engine light, flashing glow plug light and limp mode with a manual trans.

I found the Recall Info on my On-Line eBahn Repair manual software...Title: Safety Recall N4...Date: August, 2007Applicable: "All 4th generation 1999-2005 Jetta,
2001-2005 Jetta Wagons
1998-2007 New Beetle
2003-2007 New Beetle Convertables
1999-2006 Golf/GTI... AND
2004 "R32" whatever that is!
It goes on to say that all models without cruise control produced prior to 10/2000 are not affected.
And they later add that 2003-2005 5th generation Passats and Passat that p/n=3B0 945 511A NAR will not work.
The notice is 1.5 pages long and Bentley makes their software such that I canNOT simply block/copy/past the information...
and right now my eBahn program will NOT print this Recall Notice... it just bombs and goes off-line!
So think twice about buying eBahn!
IF I can get eBahn to print these 2 pages, I'll convert them to low-res JPEG and make them available to anyone who PM/Emails me!
Oh yes... the correct switch for the Passat/Passat Wagons is p/n 1K2 945 511 NAR.
But they don't clearly state what p/n is for the Jettas... maybe it's p/n 1CV0 945 511A NAR noted earlier...a most confusing document!
What I'm taking this from is a Q&A document... so this might explain the lack of specificity!
Regards,
Sam Ross